This disclosure relates generally to a thrust chamber for a centrifugal pump. More particularly, the disclosure relates to a telescoping shaft for the thrust chamber.
One type of surface pump commonly used to inject large volumes of liquid into a well is a centrifugal pump. A typical, conventional centrifugal surface pump 10 is illustrated by FIG. 1. Surface pump 10 is supported on a skid 15, and has a housing 20 with an inlet end 25 and a discharge end 30. Inlet end 25 is fluidicly coupled to an intake chamber 35. Liquid to be pressurized by pump 10 is supplied to inlet end 25 of pump 10 through intake chamber 35. Liquid that has been pressurized by pump 10 is exhausted from pump 10 through discharge end 30.
Pump 10 further includes a shaft 40 and a motor 50 operable to rotor shaft 40. Shaft 40 extends through housing 20 and a number of stages disposed therebetween. Each stage of pump 10 includes an impeller and a diffuser disposed within housing 20 about shaft 40. When shaft 40 rotates, velocity is imparted to liquid passing through pump 10 by the impellers. Interaction of the liquid with the diffusers converts the velocity to pressure. Thus, the liquid is pressurized as it passes through the multiple stages of pump 10.
In reaction to the pressure increase of the liquid, axial thrust is transferred to shaft 40 by the impellers. The thrust load is transferred along shaft 40 to bearings disposed within thrust chamber 45. Thrust chamber 45 further includes one or more mechanical seals disposed about shaft 40 proximate the locations where shaft 40 passes into and out of thrust chamber 45. These mechanical seals prevent the loss of fluid contained within thrust chamber 45 for lubricating and cooling the bearings.
During the life of a surface pump assembly, such as the one described above, the mechanical seal(s) experiences wear and must be replaced regularly, for example, every two years. Bearings in the thrust chamber also experience wear and must be rebuilt or replaced. Such maintenance operations often require the connections to the pump be disconnected and the pump physically moved to enable removal and replacement of the mechanical seal, bearings, or thrust chamber. Consequently, these operations can require a day or more of downtime to perform the necessary maintenance procedure.
Accordingly, there is a need for apparatus that enables quicker removal and replacement of the mechanical seal, bearings, or thrust chamber. It would be particularly desirable if the apparatus enabled access to the mechanical seal or thrust chamber without the necessity to disconnect and move the pump.